The present invention relates to an optical head unit for use in an optical disk device such as a magneto-optic disk or CD-ROM. More particularly, the invention relates to the construction of a movable section in a division-type optical system in which the optical system is divided into a stationary section and a movable section.
In one example of a conventional optical head unit, the optical head is linearly reciprocated in the radial direction of the optical disk with a linear motor. An optical head unit of this type, having a good head feeding response, can achieve high speed access operations.
Recently, an optical head unit of the division-type optical system has been proposed in which the optical system of the optical head is divided into a stationary section and a movable section so that the number of optical components for the movable section can be reduced as much as possible so as to minimize the weight of the movable section.
However, the optical head unit still has a large number of components and is intricate in construction because the magnetic circuit of the linear motor used for driving the optical head radially of the disk and the magnetic circuit of the objective lens actuator used for driving the objective lens in the focusing and tracking directions are provided separately from each other.
Furthermore, in the conventional optical head unit, since the movable section includes the magnetic circuit for the objective lens actuator, the movable section still has a large weight, thus obstructing the further improvement of high speed access operations.